Personally rather than BB I did create many game concepts and developed the ideas, even tried to learn coding to make it real, however the level of coding that it requires to follow any of the concepts I made was far out of my reach. A few ideas I made were:
-Adventurer's life: Overall in this game it was based on exploring dungeons and obtaining items and gifts for girls, however the bad thing is that the item may be cursed and have an effect on the girl that receives it, making her submissive or dominant, slutty or a prude, get her certain fetishes... it was quite centered on the main girls and there were 2 other adventurers that could give gifts and seduce the girls (one of them being male and the other a lesbian girl), overall it was a slice of life with main events to spice it up a bit.
-University life: This game I had two concepts over it, the common part was that we were at 3rd year on our university life and it was time for your little sister to go to university too, being accepted in the same one your parents decided that you two live together so that the cost isn't too great. The main part of the concept differed on the little sister. In one of them it was mostly based on her respect of you and her love, while the other she was a futanari that lusted for her brother but never did any advance because she considered her really weird. Overall in the university being quite a few main characters too, one being a female bully that she likes to mess with you.
-Rural life: In this one we were part of a village however we had to deal with strange cults and gods that wanted to take over the village, overall it was based on the effects that the different cults/gods have over the village and having to deal with them before they gain a lot of influence.
-Village chief life: In this one the concept was based on having to deal with external enemies such as goblins and at the start having to consolidate your power, overall after the death of your grandfather he named you as the next village chief, however the captain of the guard in the village (a veteran man soldier man quite lustful), and a female merchant with quite a lot of money and contacts want to fight you for the position. In this one the main girls could be captured in raids done by mobs like goblins and you had to rescue them.
Overall ignoring the names (which were concept names) I did quite a lot of development towards each idea but I failed badly when trying to make it into a game because I lacked the necessary knowledge and well, I suck too at making art. The main point in all games was to make the MC part of a world.